EP2435887B1 - Enhanced control of a thermostatic valve - Google Patents

Abstract

The invention relates to a valve arrangement (1), having a valve (2), which controls a flow of a heat-transfer medium through a heat exchanger arrangement, which comprises a primary side and a secondary side (11), and having a valve actuating device, which comprises a thermostat element (6), which is exposed to a temperature on the secondary side (11) and can be acted on by a temperature- and/or pressure-influencing device (14). The aim of the invention is to achieve good control behavior and fast reaction. For this purpose, the temperature- and/or pressure-influencing device (14) is influenced by a physical variable that can be determined at the valve (2) or the heat exchanger arrangement.

Description

The invention relates to a valve arrangement having a valve which controls a flow of a heat transfer medium through a heat exchanger arrangement which has a primary side and a secondary side, and a valve actuation device which has a thermostatic element which is acted upon by a temperature on the secondary side and a temperature and / or or pressure influencing device can be acted upon.

Such a valve arrangement is for example off DE 24 21 810 A1 known. The valve is designed here as a radiator valve. To achieve a night reduction, the thermostatic element is heated by a heater. The heater acts on a housing of the valve, from which warm air reaches the thermostatic element.

DE 33 11 493 A1 shows a valve assembly which is also designed as a radiator valve. Here, a thermostatic element is provided, which is not directly influenced by the room temperature, but by an electric heating element. This heating element is controlled by a PI controller, which in turn is connected to a temperature sensor with setpoint adjustment.

DE 38 21 813 C1 discloses a suitable for heating systems thermostatic valve in which the effective volume of the thermostatic element is variable by an actuator to realize a night reduction can be required in the energy only at the moment of the adjustment process.

WO 2006/029629 discloses a heat exchanger having a housing in which a primary side with a first flow path between a flow port and a return port and a secondary side with a second flow path between an inflow port and a drain port is arranged, and with a valve for controlling a flow of a heat transfer fluid through the primary side , It would like to make such a heat exchanger compact. For this purpose, it is provided that the valve has an actuating device with an expansion element, which is acted upon by the temperature on the secondary side.

• die Benutzung einer Druckbeeinflussungseinrichdng die auf das Thermostat eines Ventils wirkt, ermöglicht die Aufhebung eines statischen Fehlers,
• die Druckbeeinflussungseinrichtung is direkt vom Druck am Vorlauf des Wärmemediums beeinflusst.

Another document ( JÄTH & B MARTIN M: "Remote-controlled thermostatic valve, centrally controlled" HLH MAGAZINE FOR HEATING, VENTILATION, AIR CONDITIONING, HAUSTECHNIK, VDI VERLAG. DUSSELDORF, DE, Vol. 38, No. 1, 1 January 1987, pages 7-10 , XP002140302) describes the improvement of the operation of a thermostat with the same advantages as WO 2006/029629 , this means:

• the use of a Druckbeeinflussungseinrichdng acting on the thermostat of a valve, the resolution of a static error,
• the pressure-influencing device is influenced directly by the pressure at the flow of the heat medium.

The use of thermostatic elements to control valves that control the flow of a heat transfer fluid has been proven. Such valves, which are referred to below as "thermostatic valves", are used not only in heat exchangers which are designed as radiators, but also in heat exchangers, which are intended for domestic water heating. In such domestic water heaters, the primary side is supplied for example by a district heating system or by a heating system.

Thermostatic valves form part of a control loop. The thermostatic element has the advantage that it reacts relatively quickly to changes, such as changes in the ambient temperature, which are caused by external influences. For example, the temperature in a room may change not only due to the heat radiation from the radiator, but also due to solar radiation or a larger number of people in the room.

A disadvantage of thermostatic elements is the fact that they essentially show a proportional control behavior. This has the consequence that in most cases remains a control deviation, ie an error that distinguishes the predetermined target value of a temperature from the actually achieved actual value.

You can also control valves in other ways, for example by a motor. However, an engine usually has the disadvantage that it reacts relatively slowly. A fast reaction can be achieved by a large engine. Apart from the fact that even so often not the desired speed is feasible, a motor also has the disadvantage that it is expensive and requires a relatively large amount of space.

The invention has for its object to achieve a fast response to a good control behavior.

This object is achieved in a valve arrangement of the type mentioned above in that the temperature and / or pressure influencing device is influenced by an ascertainable on the valve or the heat exchanger assembly physical quantity.

The thermostatic element is thus not only controlled by the temperature on the secondary side. This would result in the permanent control deviation resulting from the P-control characteristic. On the contrary, the effect of the thermostatic element is additionally influenced by changing its temperature and / or the pressure prevailing in the thermostatic element. This change is not timed to effect a night dip or increase the target value for a day temperature again. The influence is rather with the aim of changing the control characteristics of the thermostatic element, due to physical parameters whose changes can be taken into account.

It is preferred that a control device is provided which determines a control deviation on the valve and controls the temperature and / or pressure influencing device as a function of the control deviation. With this embodiment, you get the opportunity to incorporate into the scheme an integral component. Depending on the way in which the control device works, it may also be possible to incorporate a differential component into the control. So one is able to effect a PI control or even a PID control. The physical quantities necessary for this regulation can be readily determined on the valve or the heat exchanger arrangement.

For example, a pressure sensor may be provided which determines a pressure in the thermostatic element. The temperature and / or pressure influencing device responds to the pressure in the thermostatic element. With this actual pressure can be compared a target pressure, which should correlate to a ruling on the secondary side of the heat exchanger assembly temperature. If the actual pressure does not match the target pressure, then the temperature and / or pressure influencing means goes into action and changes the pressure in the thermostatic element until a better match has been achieved. Even if a complete coincidence of the two pressures can not be achieved in many cases, the control characteristic of the thermostatic element is greatly improved.

It can also be provided that the valve has a valve spindle and a spindle sensor detects a position of the spindle, wherein the temperature and / or pressure influencing device responds to a spindle offset. Again, you can then correct the spindle offset, so the current position of a valve member relative to a valve seat to achieve a better match of the actual temperature on the secondary side with the target temperature.

It can also be provided that a temperature sensor on the secondary side of the heat exchanger assembly, which determines an actual temperature and a comparator, which determines a difference between the actual temperature and the target temperature, are provided, wherein the temperature and / or pressure - The influencing device reacts to the difference. If the thermostatic element is already equipped with a remote sensor, then the temperature sensor is provided in addition to the remote sensor. The temperature and / or pressure influencing device then also acts on the thermostatic element in the sense of reducing the control deviation.

Preferably, the thermostatic element has an outwardly guided connection to which an additional container is connected, wherein the temperature and / or pressure influencing device acts on the additional container. Such a configuration may be advantageous from several points of view. For example, if there is insufficient space available inside a radiator thermostatic valve topper to accommodate the temperature and / or pressure control device, it may be advantageous to place the temperature and / or pressure control device at a different position. Another advantage of an additional container is that here a larger volume of working medium can be kept, the size of which changes with a change in temperature. It is then possible to achieve a great effect on the thermostatic element itself by means of the temperature and / or pressure-influencing device even with lower pressure or temperature changes.

Preferably, the temperature and / or pressure-influencing device is operable in a heat-emitting state and in a heat-receiving state. The temperature and / or pressure influencing device can thus cool the thermostatic element when it absorbs heat or heat when it gives off heat. This additionally expands the possibilities of influencing the thermostatic element.

It is particularly preferred that the temperature and / or pressure influencing device has a Peltier element. A Peltier element can heat or cool, whereby these two functions can be adjusted relatively easily by an appropriate power supply of the pelletizing element.

In a particularly preferred embodiment, it is provided that the heat exchanger assembly is designed as a hot water heater with primary inlet and primary outlet on the primary side and secondary inlet and secondary outlet on the secondary side, with the secondary drain hot water with elevated temperature is removable. The temperature of the service water is determined by a temperature sensor on the secondary run. This temperature then controls the valve located on the primary side, either in the primary inlet or in the primary outlet. In a hot water heater arise at the beginning of a tapping process for hot water relatively large temperature jumps. These temperature jumps can be compensated relatively quickly by the thermostatic element. In addition, the temperature and / or pressure influencing device is advantageously used to reduce the permanent control deviation.

Preferably, the temperature and / or pressure influencing device is influenced by a temperature at the primary inlet. This temperature is then the physical quantity at the heat exchanger arrangement, with the help of which the control deviation is reduced.

In this case, it is provided in a particularly preferred embodiment that the temperature and / or pressure influencing device has a heat-conducting connection between the primary inlet and the thermostatic element. The temperature from the primary inlet is then transferred via the heat-conducting connection practically directly to the thermostatic element. In this relatively simple manner, it is ensured that the valve receives an improved valve behavior.

It is preferred that the heat-conducting connection is formed by a metal wire, in particular of copper, which is in heat-conducting contact with the primary inlet and the thermostatic element. In the simplest case, the metal wire can simply be wound several times around the primary inlet and also several times around the thermostatic element. When using copper or a metal with similarly good thermal conduction properties, an excellent control behavior can then be realized in a simple manner.

In an alternative or additional embodiment, the heat-conducting connection can also be designed as a pipeline, in particular as a capillary line, which is connected to the primary inlet. In this case, one uses the pressure difference across the heat exchanger to drive the liquid through the pipeline and thus to transport the heat.

Fig. 1

eine schematische Darstellung einer Ventilanordnung,

Fig. 2

eine Wärmetauscheranordnung mit einer Ventilanordnung,

Fig. 2a

eine zu Fig. 2 abgewandelte Ausführungsform einer Wärmetauscheranordnung,

Fig. 3

eine schematische Darstellung zur Erläuterung eines Offnungsverhaltens des Ventils und

Fig. 4

eine schematische Darstellung zur Erläuterung eines abgewandelten Öffnungsverhaltens,

Fig. 5

eine zu Fig. 1 abgewandelte Ausführungsform und

Fig. 6

eine weitere Wärmetauscheranordnung.

The invention will be described below with reference to preferred embodiments in conjunction with a drawing. Herein show:

Fig. 1

a schematic representation of a valve assembly,

Fig. 2

a heat exchanger arrangement with a valve arrangement,

Fig. 2a

one too Fig. 2 modified embodiment of a heat exchanger assembly,

Fig. 3

a schematic representation for explaining an opening behavior of the valve and

Fig. 4

a schematic representation for explaining a modified opening behavior,

Fig. 5

one too Fig. 1 modified embodiment and

Fig. 6

another heat exchanger assembly.

A valve assembly 1 according to Fig. 1 has a valve 2 with a valve element 3 and a valve seat 4. The valve element 3 is fastened to a valve spindle 5. The valve spindle 5 is actuated by a thermostatic element 6. In the thermostatic element 6, a working medium 7 is arranged, the volume of which changes with temperature. The working medium 7 may be liquid or gaseous or a mixture of liquid and gas. It can be a solid, such as wax. An absorbent medium is also possible. The enumeration of the types of working media should not be conclusive here.

The valve element 3 is acted upon by an opening spring 8 with a force away from the valve seat 4. The pressure in the thermostatic element 6 acts against the force of the opening spring in the closing direction.

The valve 2 controls the flow of heat transfer fluid from an inlet 9 into a drain 10, which is connected in a manner not shown with a heat exchanger, such as a radiator, radiator or hot water heater. The following explanation of the embodiment of Fig. 1 assumes that this radiator heats a space 11 in which a remote sensor 12 is arranged, which is connected by a capillary 13 to the thermostatic element 6. When the temperature in the room 11 rises, the working fluid 7 expands in the remote sensor 12 and is displaced by the capillary 13 into the thermostatic element 6. This increases the volume within the thermostatic element 6, so that the valve spindle 5, the valve element 3 further approaches to the valve seat 4 and throttles the flow of heat transfer fluid into the heat exchanger. Accordingly, the temperature in the room 11 no longer increases or even decreases. When the temperature in the room 11 decreases, then decreases the volume of the working medium 7 in the remote sensor 12, so that the opening spring 8 can remove the valve element 3 again from the valve seat 4. This increases the influx of heat transfer fluid.

If the thermostatic element 6 is arranged in the space 11, a remote sensor 12 is often unnecessary.

Such a thermostatic element acts as a proportional controller (P-controller). Such a P-controller has a permanent control deviation.

In order to reduce this permanent control deviation, a temperature and / or pressure influencing device 14 is provided, which acts on the thermostatic element 6 or an additional container 16 connected thereto via a line 15. The additional container 16 also contains working medium. 7

The additional container 16 is in communication with a Peltier element 17, which is controlled by a control device 18. The Peltier element 17 can both heat the auxiliary reservoir 16 when it gives off heat and cool it when it absorbs heat. The Peltier element 17 can also be placed in a neutral state in which it neither absorbs heat from the additional container 16 nor gives off heat to it.

The control device 18 in turn is subjected to an error F, which is shown schematically here. This error is generally a control deviation caused by the thermostatic element 6. The error F can be concretized in different ways. It is possible to arrange a pressure sensor 19 in the thermostatic element 6, which determines the pressure in the working medium 7. It is possible to use a spindle sensor 20 which determines the position of the spindle 5 and thus a spindle offset, ie a difference between an expected target position of the spindle 5 and an actually existing position of the spindle 5. It is also possible to use an additional temperature sensor 21 which determines the actual temperature in the space 11 and compares it with a desired temperature. The three sensors 19-21 are connected to the control device 18, these connections not being shown here for reasons of clarity. A box 100 is intended to represent the position at which one or more of the sensors 19-21 are shown in terms of circuit technology relative to the control device 18.

Of course, one can also arrange the Peltier element 17 (or another tempering device) directly on the thermostatic element 6. In this case, one can also change the effect of the thermostatic element 6 independently of the influence of the temperature in the space 11. In particular, one can reduce an error caused by a permanent control deviation. Nevertheless, the rapid reaction that characterizes a thermostatic element 6, also for the control of the valve 2 is maintained.

Fig. 2 shows an embodiment in which the valve 2, which is shown here only schematically, in conjunction with a hot water heater 22 is shown. The hot water heater 22 is a heat exchanger having a primary side 23 and a secondary side 24. The primary side 23 has a primary inlet 25 and a primary outlet 26. The secondary side has a secondary inlet 27 and a secondary outlet 28. The primary side 23 communicates, for example, with a district heating network or a home heating system. On the secondary side 24, a consumer can remove hot water.

In the secondary run 28, a temperature sensor 29 is arranged, which is connected to the thermostatic element 6. When a consumer taps warm water, then the temperature at the secondary outlet 28 drops and the valve 2 opens stronger, so that on the primary side 23 an increased flow of heating fluid can take place.

A heat conducting connection 30 is established between the primary inlet 25 and the thermostatic element 6. The heat conductive connection 30 is formed in the simplest case by a copper wire 31 or a wire made of another good heat conducting material, which is wound around the primary inlet 25 and also to the thermostatic element 6. It can also by a with water or other fluid filled conduit 31a ( Fig. 2a ), wherein the fluid takes over the heat transfer, for example, also by heat conduction or by convection. As a result, the thermostatic element 6 receives approximately the temperature of the primary inlet 25. In Fig. 2a are the same and functionally identical elements as in Fig. 2 provided with the same reference numerals. The fluid can be driven by the pressure difference across the heat exchanger 22 through the capillary 31a.

The function is now based on the FIGS. 3 and 4 be explained in more detail. 3 and 4 show a valve characteristic with the sensor temperature along the X-axis and the degree of opening along the Y-axis. In Fig. 3 When the temperature of the thermostatic element 6 is increased, the line 32 shifts to the line 33. When the temperature of the thermostatic element is lowered, the line 32 shifts to the line 34 Depending on the operating point of the thermostatic element (for example, the point at which the valve 2 opens), the temperature of the thermostatic element 6 can be adjusted so that the temperature at the secondary run 28, as determined by the temperature sensor, is the same for all operating points. This is represented by a vertical line 35.

The introduction of an I term in the form of a temperature change of the thermostatic element 6 allows a reduction in the gain in the control loop without an increase in the residual deviation. In other words, the temperature deviation of the tapped water at the secondary run 28 becomes smaller or even disappears altogether. This in turn leads to an increased stability of the control loop. This is in Fig. 4 shown. Again, a line 32 shows the normal operating state of the thermostatic element 6, a line 33 shows the performance at an elevated temperature of the thermostatic element 6 and a line 34 the performance at a reduced temperature of the thermostatic element 6. To the right is in the FIGS. 3 and 4 The temperature of the sensor 29 is plotted and the flow on the primary side 23 is plotted upward. It can be seen that the line 36 has an inclination, ie the temperature deviation of the tapped hot water at the secondary run is greater than in the embodiment according to FIG Fig. 3 , However, it is still within a tolerable range.

Fig. 5 shows a schematic representation of a valve arrangement, which is substantially according to Fig. 1 equivalent. The same and functionally identical elements are therefore provided with the same reference numerals.

Modified is the influencing device 14a for the thermostatic element 6, which influences only the pressure of the working medium 7 in the thermostatic element 6 in this embodiment. For this purpose, the additional container 16 is connected to a pressure-influencing device 37 shown only schematically, which in turn is controlled by the control device 18. The pressure-influencing device 37 influences the pressure of the working medium 7 in the thermostatic element 6. For this purpose, it can, for example, change a volume in the additional reservoir 16 filled with the working medium 7. The pressure influencing device 37 may have different configurations. It can be designed for example as a pump, servo-actuator or diaphragm actuator.

Fig. 6 shows an embodiment, which is a further development of the embodiment Fig. 2 is. Same elements as in Fig. 2 are therefore provided with the same reference numerals.

The heat exchanger arrangement according to Fig. 6 has in addition to the hot water heater 22 on another heat exchanger 40, which is provided for the supply of radiators 41 in a heating system. A pump 42 generates a forced circulation of heat transfer fluid through the radiators 41 and the Secondary side 43 of the heat exchanger 40. The primary side 44 of the heat exchanger 40 is also connected to the primary inlet 25 and the primary outlet 26, which belong for example to a district heating network.

The flow of the heat carrier on the primary side 44 is controlled by a valve 45, which in turn is actuated by a thermostatic element 46 or otherwise, for example an electrically driven motor. The thermostatic element 46 is influenced by a temperature sensor 47 on the secondary side 43.

The thermostatic element 6, which controls the valve 2 for the hot water heater 22, however, is connected via the heat-conducting connection 30 to the primary inlet 48 and the primary outlet 49 and therefore subjected to the heat from the primary side 44 of the heat exchanger 40. This can be taken into account in an advantageous manner that there are different temperature conditions in a district heating in summer and winter.

For example, the temperature of the heat transfer medium of a district heating network in winter is 100 ° C. In addition, the radiators 41 must be supplied with heat, so that the heat exchanger 40 is active. Since the heat conductive connection 30, the primary side 44 of the heat exchanger 40 is applied to the thermostatic element 6 of the valve 2 for the hot water heater 22, this results in a decreasing temperature deviation for the thermostat of the controlled control loop and thus an enlarged P-band.

In summer, the temperature of the heat transfer medium of the district heating network is typically lower. It is for example 65 ° C. In summer, the radiators 41 are not in operation. Accordingly, the heat exchanger 40 does not have to work because there is virtually no heat requirement to heat a house. This means that the thermostatic element 6 is not heated via the primary side 44 of the heat exchanger 40. This results in a normal control deviation.

Claims (12)

1. Valve arrangement with a valve controlling a flow of a heat carrying medium through a heat exchanger arrangement that comprises a primary side and a secondary side, and with a valve actuating arrangement that comprises a thermostatic element that is acted upon by a temperature on the secondary side and can be acted upon by a temperature and/or pressure influencing arrangement, the temperature and/or pressure influencing arrangement (14, 30) being influenced by a physical value that can be measured at the valve (2) or the heat exchanger arrangement (22), characterised in that a control arrangement (18) is provided to detect a control deviation at the valve (2) and to control the temperature and/or pressure influencing arrangement (14) in dependence of the control deviation.
2. Valve arrangement according to claim 1, characterised in that a pressure sensor (19) is provided to measure a pressure in the thermostatic element (6), the temperature and/or pressure influencing arrangement (14) reacting to the pressure.
3. Valve arrangement according to one of the claims 1 or 2, characterised in that the valve (2) comprises a valve spindle (5) and a spindle sensor (20) detects a position of the spindle, the temperature and/or pressure influencing arrangement (14) reacting to a spindle displacement.
4. Valve arrangement according to one of the claims 1 to 3, characterised in that on the secondary side (11, 24) of the heat exchanger arrangement a temperature sensor (21) is provided to determine an actual temperature, and a comparator is provided to determine a difference between the actual temperature and the desired temperature, characterised in that the temperature and/or pressure influencing arrangement (14) reacts to the difference.
5. Valve arrangement according to one of the claims 1 to 4, characterised in that the thermostatic element (6) comprises a connection (15) that is led to the outside and to which an additional tank (16) is connected, the temperature and/or pressure influencing arrangement (14) acting upon the additional tank (16).
6. Valve arrangement according to one of the claims 1 to 5, characterised in that the temperature and/or pressure influencing arrangement (14) can be operated in a heat supplying state and in a heat receiving state.
7. Valve arrangement according to claim 6, characterised in that the temperature and/or pressure influencing arrangement (14 is made as a Peltier element.
8. Valve arrangement according to one of the claims 1 to 7, characterised in that the heat exchanger arrangement is made as a domestic water heater (22) with a primary inlet (25) and a primary outlet (26) on the primary side and a secondary inlet (27) and a secondary outlet (28) on the secondary side (24), the secondary outlet (28) supplying domestic water with increased temperature.
9. Valve arrangement according to claim 8, characterised in that the temperature and/or pressure influencing arrangement (30) is influenced by a temperature at the primary inlet (25).
10. Valve arrangement according to claim 9, characterised in that the temperature and/or pressure influencing arrangement (30) comprises a heat conducting connection (31) between the primary inlet (25 and the thermostatic element (6).
11. Valve arrangement according to claim 9 or 10, characterised in that the heat conducting connection (31) is made as a tube, preferably as a capillary tube, that is connected to the primary inlet (25).
12. Valve arrangement according to claim 10, characterised in that the heat conducting connection (31) is formed by a metal wire, in particular copper, that is in heat conducting contact with the primary inlet (25) and the thermostatic element (6).

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